Electromagnetic switch



March .925

J. F. TRITLE ELECTROMAGNETIC SWITCH Filed Nov. 18, 1926 Im/en'L-orw John Fri-tale His Attorney.

Patented Mar. 24, 1925.

UNITED STATES 1,5351 PATENT OFFICE,

JOHN F. TRITLE, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTROMAGNETIC SWITCH.

Application filed November 18, 1920.

To all whom it may concern.-

Be it known that I. JOHN F. TRITLE, a citizen of the United States, residing at Schenectady,- county of Schenectady, State of New York, have invented certain new and useful Improvements in Electromagnetic Switches, of which the following is a specification.

My invention relates to improvements in shock-proof electric switches and in particular to electromagnetic switches which may be controlled at the will of the operator or automatically in response to a predetermined condition and which will not open due to the shocks, vibrations, or jars to which apparatus of this character is ordinarily subjected.

One of the objects of my invention is to provide an electric switch which will be caused to be locked in the operated position and the locking effect caused to be maintained substantially unaltered during shock and jars to which the switch may be subjected.

More particularly my invention relates to improvements in electromagnetic switches which are electromagnetically operated to the closed position and then mechanically held in that position with the operating electromagnet deenergized. Furthermore, in accordance with my invention, I provide improved means whereby an electromagnetically operated, mechanically held switch of the character indicated is automatically opened in response to predetermined conditions in the circuit controlled by the switch,

as for instance, in response to an overload in the circuit.

For a better understanding of my invention, reference is had to the accompanying drawings wherein I have shown my invention embodied in concrete form for purposes of illustration and in which Fig. 1 is a side view of the electromagnetic switch shown located in the closed position; Fig. 2 is a plan view of the same; Fig. 3 is a detail of the magnetic circuits for the operating electromagnet; Fig. 4 is a view similar to Fig.

1 showing the relation of the various parts at the instant the overload device has operated to release the switch member, with the switch member being shown as having dropped to the open position; and Fig. 5 is a simplified diagram of amotor. control ar rangement embodying invention, i

Serial No. 42%,991.

Referring to the drawings, the switch comprises a switch member having two movable contact discs 10 and 11 secured thereto. The contactdisc 10 cooperates with the sta tionary contacts 12, and. the disc 11 cooperates with the stationary contacts 13. These movable contact discs 10 and 11 are mounted on an operating rod 14: so as to be movable longitudinally with respect thereto. The downward movement of the disc 11 with respect to the rod 14 is limited by means of the collar 15 secured on the rod, and the downward movement of the disc 10 with respect to the rod is limited by means of the collar 16, which is also secured to the.

rod. Between the disc 10 and the collar 16 there is interposed a spring 17 provided for the purpose of resiliently mounting the disc 10. A collar 18 is secured on the end of the rod 1 1, This collar cooperates with the plunger 19 of the operating electromagnet of the switch. The magnetic structure of the operating electromagnet comprises the core 20, the magnetic supporting member 21 and'the plunger 19. The winding 22 is provided for energizing the magnetic structure so as to cause the switch member to be moved to the position shown in Figs. 1 and 2 at which the upper contact disc 10 makes engagement with its stationary contacts 12, and the lower disc 11 is out of engagement with its stationary contacts 13.

A bell crank lever 23 which is pivotally mounted at 24: has one arm thereof pivotally connected to the operating rod 1 1 at 25. The other arm of the bell crank lever is provided with a roller 26 on its end which cooperates with a cam surface 27 on the locking lever 28 which has a pivotal support between the pivotal support of the bell crank lever and the switch rod 14. The pivoted locking lever 28 is biased tothe position shown on the drawing (Fig. 1) by means of the spring 29, the tension of which is adjustable by means of the adjusting screw 30. The pivoted locking lever 28 is made of any suitable magnetic material and serves as the armature or movable member of an electromagnetic device responsive to conditions in the electric circuit. In the arrangement which I have selected for the purpose of illustration, this device is an over load device and comprises the member 31 of magnetic material which is of the form shown in the figures and adapted to substantially embrace the straight conductor 32 which 'is in the circuit controlledby the switch. Although the conductor 32is'shown as a straight conductor, my invention is not necessarily limited thereto. The magnetic member 31 is suitably secured to the conductor 32 by means of the bolt 33 and also secured to the magnetic structure 21 of the operating electromagnet by means of the bolt 34. The bolt 35 provides additional means for securing the switch in position with respect to the conductor 32.

It will be observed that the magnetic structure for the overload device comprises the magnetic members 31, 21, and the armature 28, and it will also be observed that this armature 28 acts as a wedge to lock the switch in the operated position; that is, in such a position that the contact disc .10 is in engagement with its stationary contacts, even though the operating winding 22 is deenergizedl The plunger 19 is constructed as shown to provide a loose connection with the rod 14 in order that when. the winding 22 is '(leenergizechthe plunger will drop to the position shown in Fig. 3 so as to mtroduce an air gap between itself and the core 20 which will be-ofusuch length that the flux through the magnetic structure of the overload device will not cause the plunger 19 to be held in position and thereby defeat one of the objects of the invention.

Referring to Fig. 5, the electric motor 36 is adapted to be energized from the source of en 1y 3 in res Jonse to the closin of PP l e the line contact-ore 38 and 39. A starting resistor 450 is included in the motor armature circuit, and this resistor is adapted to be short circuited by'means of the contactor 41. My improved electromagnetic switch is diagrammatically shown on this figure, andthe manner in which the switch is adapted to control the motor will be understood from a description of Fig. 5. The master controller 42 which is adapted to govern the various electromagnetic switches is shown in the oil" position, and my improved electromagnetic switch is shown in the position in which the upper contact disc 10 islocked in engagement with its stationary contacts by means of the lever or armature 28 cooperating with the bell crank lever 23;

/Vith the parts in the various positions shown, in order to start the motor, the master controller 42 is first turned-1 to the first position. The line contactors 38 and 39iare thereby energized to close" and connect the motor through the resistor lOto the battery 37, the circuit for the windings of the contactors 38 and'39= being through the contact disc lO'and the middle segment ofthe controller'. After. the motorhas accelerated" so that it is safe to shortcircuit'the resistor 40, the mas e con ll r t2 'Wihjbe mo ed-t0 the curely locks the switch member inposition,

so that the switch member can not drop and during, any sllght upward movement, such as occas oned by shocks and ars, the locking effect is maintained. However, in case there should be an overload on the motor, the conductor 32 will carry such a current that the magnetic structure of the overload device will be sufficiently energized to attract the armature 28 against the bias of the spring 29, thereby permitting the switch member to drop, so that the upper contact "disc 10 opens the circuit for the windings ofline contactors 38 and 39, andimmediately thereafter, the contact disc 11 bridges the stationary contacts 13. The roller 26permits the armature to be readily raised" without stick ng since the upward movement of the armature causes the roller to rotate. The line contactors 38 and 39 will open, and the'motor will be disconnected from its source of supply.

Fig. at shows the position of the various parts at the instant my improvedswitch has opened its upper set of contacts and closed the lower, and before the armature 28 has returnedto its biased position due to the decnergization ofthe magnetic structure of the OVGllOflCl'dGVlCG causedby the opening of the line contactors 38. and 39. hen the armature 28 is no longer attracted, it will drop, and the projection 43'having the cam surface 27 will drop into engagement with the roller 26 on the one arm of the bell crank lever. 23.

In order to reconnect the motor to the battery. 37', the controller 42 must be returned to its off position at whichthe resistor contactor 4:1 is deenergized and tlie'winding 22 ofiny protective switch is energized through the disc 11 and the stationary contacts 13. The energization of the winding 22 will cause the plunger 19 to bedrawn upwardly so as to. engage the collar 18 and movethe operating rod 14, thereby openingthe circuit through the contacts-13 and closing the circuit through the contacts 11. The upward movementof the contacts also moves the bellcrank; lever 23, andthe armature 28" is permittedto drop further into such a position that the cam surface 27 engages th'e'roller 26and looks" or wedges the switch member in its attracted position. The switch will therefore not reopen by reason'of the'deenergizatio'n ofits winding caused by the opening of the circuit of" the: stationary" con a t 13. When the winding 22 is deenergized, the plunger 19 will return to its lowermost position, that shown in Fig. 3, for the purpose heretofore explained.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together wtih the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the ap paratus shown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,

l. The combination in an electric switch, of a movable switch member, a bell crank lever pivotally supported laterally from the line of movement of the switch member and having one arm connected to the switch member, and a cam pivotally mounted and arranged to cooperate as a wedge with another arm of the bell crank lever for holding the switch member in a predetermined position.

2. The combination in an electric switch, of a movable switch member biased to one position, means for holding the switch member in another position against its bias to the first position, comprising a pivotally mounted bell crank lever having one arm connected to the switch member and another arm )rovided with a roller, and a pivotally mounted holding member cooperating with the said roller, the said holding member having a cam surface which engages with the said roller to permit of minor relative movements between the said switch member and the holding member while the switch member is held in the said other position.

3. The combination in an electromagnetic switch, of a movable switch member, an electromagnet for operating the same, a holding member of magnetic material for holding the switch member in the operated position with the electromagnet deenergized, and a magnetic structure adapted to substantially surround a conductor of the electric circuit controlled by the switch, the said holding member serving as an armature for the said magnetic structure, whereby the holding member is moved to release the switch member responsively to conditions in the said electric circuit.

4. The combination in an electric switch, of a movable switch member biased to one position, a holding member of magnetic ma terial biased to a position at which it holds the switch member in another position against its bias to the first position, an elec tromagnet comprising a member of magnetic material adapted to substantially surround an electric conductor for attracting the holding member to release the switch member in accordance with the current in the said conductor.

5. The combination in an electric switch, of a movable switch member biased to one position, a holding member of magnetic material for holding the switch member in another position against its bias to the first position, an electromagnet comprising a member of magnetic material adapted to be clamped around a substantially straight conductor for attracting the holding member to release the switch member in accordance with the current in the said conductor.

6. The combination in an electromagnetic switch, of an operating electromagnet therefor a movable switch member biased to one position and operated to another position against its bias by the electromagnet, an armature for holding the switch member in the operated position, and an electromagnet having a magnet structure which includes a part of the magnet structure of the operating electromagnet for attracting the armature to release the switch member in accordance with the current in the electric circuit controlled by the switch.

7 The combination in an electromagnetic switch, of an operating electromagnet therefor having a core and a movable member, a switch member biased to one position and operated to another position against its bias by the movable member of the electromagnet, a loose connection between the movable member of the magnet and the switch member whereby the movable member is adapted to introduce an air gap between itself and the core of the electromagnet when the electromagnet is deenergized, a lever connected to the switch member, and a pivoted holding member cooperating with the lever for holding the switch member in the operated position.

In witness whereof, I have hereunto set my hand this 17th day of November, 1920.

JOHN F. TRITLE. 

